Method and apparatus for allocating communication resources using virtual circuit switching in a wireless communication system and method for transmitting and receiving data in a mobile station using the same

ABSTRACT

A method and apparatus using Virtual Circuit Switching (VCS) in a new scheme are provided for allocating and employing resources by combining Circuit Switching (CS) and Packet Switching (PS), in which a base station allocates resources of a dedicated channel using the CS to a user and then transmits data on the dedicated channel. When data is not transmitted to the user, the base station allocates the allocated dedicated channel resources for resources of a shared channel and transmits data of a different user. Therefore, system capacity can be increased and a waste of communication resources can be minimized in a wireless communication system for frequently transmitting a small amount of traffic that is sensitive to a delay time.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/501,231, filed Aug. 9, 2006, now U.S. Pat. No. 7,948,941 which claimsthe benefit under 35 U.S.C. §119(a) of Korean Patent Applications filedin the Korean Intellectual Property Office on Aug. 9, 2005, and Mar. 31,2006, and bearing Serial Nos. 2005-72782 and 2006-29938, respectively,which are all incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method and apparatus forallocating communication resources in a wireless communication system.More particularly, the present invention relates to a method andapparatus for efficiently allocating and employing communicationresources in a wireless communication system using circuit switching andpacket switching and a method for transmitting and receiving data in amobile station using the same.

2. Description of the Related Art

Conventionally, communication resource allocation schemes for use in awireless communication system are classified into two schemes of CircuitSwitching (CS) and Packet Switching (PS). In the CS scheme, a fixedamount of radio resources, that is, a dedicated channel, is allocated toa particular user and data is transmitted and received using thededicated channel.

FIG. 1 is a flowchart illustrating a process for transmitting data usingthe conventional CS scheme. An example of the conventional CS scheme foruse in a transmitter of a Base Station (BS) for allocating a dedicatedchannel will be briefly described with reference to FIG. 1.

In step 101 of FIG. 1, the transmitter of the BS allocates the dedicatedchannel by performing a scheduling process for allocating communicationresources to a particular user linked through a radio network. In atypical example of step 101, a particular Walsh code for identifying achannel is allocated to the particular user in a wireless communicationsystem using Code Division Multiple Access (CDMA). In another example,particular subcarrier resources are allocated to the particular user ina wireless communication system using Orthogonal Frequency DivisionAccess (OFDMA).

To allocate the dedicated channel, the operation for allocating theparticular Walsh code or the particular subcarrier resources to theparticular user is conventionally performed in a call setup or handoffprocess. In FIG. 1, steps 103, 105 and 107 are processes fortransmitting data on the allocated dedicated channel while a call of theparticular user is connected. That is, in step 103, the transmitter ofthe BS determines whether there is data to be transmitted to a userconnected by CS (hereinafter, referred to as a CS user) for which thededicated channel has been allocated in step 101 in an associatedtransmission interval. Herein, the transmission interval means aTransmission Time Interval (TTI) or frame serving as a time unit inwhich data of one packet is transmitted.

If data to be transmitted to the associated CS user is present in thistransmission interval as a determination result of step 103, thetransmitter of the BS transmits data on the dedicated channel allocatedto the CS user in step 105. However, if data to be transmitted to theassociated CS user is not present in this transmission interval as thedetermination result of step 103, the transmitter of the BS proceeds tostep 105 to move to the next transmission interval. Then, thetransmitter of the BS again determines whether data to be transmitted tothe associated CS user is present in step 103. Until a call isterminated, the process is repeated. The communication resourceallocation process based on the CS in FIG. 1 has a problem in that adedicated channel allocated to the particular user cannot be allocatedto a different user in the same transmission interval when data to betransmitted to the particular CS user is not present in the associatedtransmission interval.

FIG. 2 is a flowchart illustrating a process for transmitting data usingthe conventional PS scheme. An example of the conventional PS scheme foruse in a transmitter of a BS for allocating a shared channel will bebriefly described with reference to FIG. 2.

The PS scheme employs shared system resources (for example, Walsh codesof a CDMA system, subcarriers of an OFDMA system, and the like) withoutallocating a dedicated channel to a particular user, which is differentfrom the CS scheme. That is, the wireless communication system using thePS scheme performs a scheduling process by determining whether toallocate system resources to a certain user in every transmission time.In step 201 of FIG. 2, the transmitter of the BS performs a schedulingprocess by determining whether to transmit data to a certain user inthis transmission interval through an internal scheduler (notillustrated) and then allocates a shared channel to the associated user.According to a scheduling result, multiple users can be simultaneouslyassigned the shared channel.

An amount of user-by-user transmission data and an amount ofcommunication resources required for a data transmission are set in thescheduling process of step 201. In step 203, the transmitter of the BSnot transmits data on the shared channel allocated to the user accordingto the scheduling result, but also transmits shared channel controlinformation on a Shared Control Channel (SCCH) such that the sharedchannel can be received. Conventionally, the shared channel controlinformation includes a user Identifier (ID), resource information, datarate information, modulation information, coding information, and thelike.

The user ID is assigned to a user in a call setup or handoff process. AMobile Station (MS) detects the user ID from the shared control channel.When multiple users simultaneously receive the shared channel, the MScan detect its own transmitted data in an associated transmissioninterval. The resource information is about communication resources usedfor a data transmission. The data rate information indicates atransmission rate of data to be transmitted in each transmissioninterval. The modulation information indicates a modulation scheme usedto transmit data such as Quadrature Phase Shift Keying (QPSK), 8-PhaseShift Keying (8PSK), and 16-Quadrature Amplitude Modulation (16QAM), andthe like. The coding information indicates a coding method and a coderate used in a transmission process.

After transmitting control information and data on the shared controlchannel and the shared channel in step 203, the transmitter of the BSmoves to the next transmission interval in step 205 and repeats theprocess from step 201 until a call is terminated.

The above-described CS or PS scheme has the following advantages anddisadvantages.

First, the CS scheme is advantageous in that an amount of controlinformation for data to be transmitted is reduced because a dedicatedchannel is allocated and the data is transmitted on the dedicatedchannel. However, the CS scheme is disadvantageous in that theefficiency of using communication resources is degraded because adifferent user cannot employ resources of the associated dedicatedchannel when there is not data to be transmitted to a user to which thededicated channel is allocated. Further, the PS scheme is advantageousin that the throughput of a wireless communication system in whichavailable communication resources are limited can be improved byselecting a user with a better radio channel environment, schedulingradio channel allocation, and maximizing channel-dependent schedulinggain. However, the PS scheme is disadvantageous in that a significantamount of control information should be transmitted together with datain every time because the shared channel is used. In the CS scheme, itis difficult for the channel-dependent scheduling gain guaranteed in thePS scheme to be expected.

For example, one of communication services to which the CS or PS schemeis applicable is a Voice over Internet Protocol (VoIP) service proposedto provide a voice service through an IP network. With the developmentof the IP network such as the Internet, the VoIP service can providehigh-quality voice communication by overcoming a voice bandwidth of 56kbps of a transmission circuit network. In the VoIP service, an overseascall can cost-effectively be used when a fee for using the Internet ispaid. Further, the VoIP service can provide various applicationsolutions and additional services. Thus, the number of users of the VoIPservice is rapidly increasing.

FIG. 3 illustrates a process for transmitting voice traffic in theconventional VoIP service.

In FIG. 3, reference numeral 301 denotes an output of a vocoder forencoding an analog voice signal into a digital voice signal. Asillustrated in FIG. 3, an ON period and an OFF period are dividedaccording to whether the output of the vocoder is an output of a soundinterval in which a user speaks or an output of a mute interval in whichthe user does not speak. A small amount of data is continuouslygenerated in a short period (for example, 20 ms) in the conventionalvoice traffic. Thus, when the VoIP traffic arrives at a BS through an IPnetwork, a received signal is irregular because VoIP packets havedifferent IP network delay times as indicated by reference numeral 302.

The above-described CS or PS scheme is used to transmit a VoIP packet. Asystem for transmitting a VoIP packet in the CS scheme may notefficiently employ communication resources because a waste ofcommunication resources is large during the OFF period as indicated byreference numeral 301 of FIG. 3. On the other hand, a system fortransmitting a VoIP packet in the PS scheme transmits the VoIP packetwith a small amount of data in a short period. In this case, there is aproblem in that data should be transmitted together with controlinformation for a packet reception in every time because of irregularcharacteristics as indicated by reference numeral 302 of FIG. 3.

Accordingly, there is a need for an improved method and apparatus forincreasing system capacity and minimizing communication resources in awireless communication system.

SUMMARY OF THE INVENTION

An aspect of exemplary embodiments of the present invention is toaddress at least the above problems and/or disadvantages and to provideat least the advantages described below. Accordingly, an aspect ofexemplary embodiments of the present invention is to provide a methodand apparatus for allocating communication resources using virtualcircuit switching that can efficiently allocate and employ communicationresources in a wireless communication system using circuit switching andpacket switching.

It is another aspect of exemplary embodiments of the present inventionto provide a method and apparatus for allocating communication resourcesusing virtual circuit switching that can minimize a waste ofcommunication resources in a wireless communication system forfrequently transmitting traffic of a small amount of data with anirregular delay time.

It is yet another aspect of exemplary embodiments of the presentinvention to provide a method and apparatus for transmitting andreceiving data in a mobile station using virtual circuit switching thatcan efficiently allocate and employ communication resources in awireless communication system using circuit switching and packetswitching.

In accordance with an aspect of exemplary embodiments of the presentinvention, there is provided a method for allocating communicationresources to transmit data to multiple user Mobile Stations (MSs) in awireless communication system, in which a dedicated channel is allocatedto a particular user MS; whether data to be transmitted to theparticular user MS is present is determined; and resources of thededicated channel are allocated for resources of a shared channel whenthe data to be transmitted to the particular user MS is not present.

In accordance with another aspect of exemplary embodiments of thepresent invention, there is provided a method for allocatingcommunication resources to transmit data to multiple user MobileStations (MSs) in a wireless communication system, in which a dedicatedchannel is allocated to a particular user MS; and a shared channel isadditionally allocated to the particular MS when an amount of data to betransmitted to the particular user MS is more than capacity of theallocated dedicated channel.

In accordance with another aspect of exemplary embodiments of thepresent invention, there is provided an apparatus for allocatingcommunication resources to transmit data from a Base Station (BS) tomultiple user Mobile Stations (MSs) in a wireless communication system,in which a data buffer temporarily stores user-by-user data to betransmitted to the multiple user MSs; a resource allocator performs ascheduling process for allocating a dedicated channel to a particularuser MS and allocating resources of the dedicated channel for resourcesof a shared channel when data to be transmitted to the particular userMS is not present; and a transmitter transmits the user-by-user dataoutput from the data buffer on radio channels allocated to users in adesignated interval according to a scheduling result.

In accordance with another aspect of exemplary embodiments of thepresent invention, there is provided a method for receiving data in auser Mobile Station (MS) of a wireless communication system, in whichallocation of a dedicated channel is received for receiving data from aBase Station (BS); a shared control channel is monitored and controlinformation is received for the data reception; and data transmitted onthe dedicated channel is received and the data from the shared channelis received when determining that the data of the MS is transmitted onthe shared channel according to a result of receiving the controlinformation.

In accordance with another aspect of exemplary embodiments of thepresent invention, there is provided an apparatus for receiving datafrom a Base Station (BS) in a user Mobile Station (MS) of a wirelesscommunication system, in which a control channel demodulator demodulatesa downlink signal and receives control information relating to a sharedchannel; a data channel demodulator demodulates a signal received from aradio channel and outputs packet data; and a data demodulationcontroller controls a reception of a dedicated channel and controls thedata channel demodulator to demodulate a signal received from the sharedchannel when determining that data of the MS is transmitted on theshared channel according to a result of receiving the controlinformation.

In accordance with another aspect of exemplary embodiments of thepresent invention, there is provided a method for transmitting data in aMobile Station (MS) of a wireless communication system, in whichallocation of a dedicated channel for a data transmission is receivedfrom a Base Station (BS); a shared control channel is monitored andcontrol information is received for the data transmission; whetherresources of the dedicated channel are allocated to a different user MSis determined through the control information; and the data transmissionis performed using remaining resources obtained by excluding resourcesof persistent resource allocation from the resources of the dedicatedchannel when resource allocation for the different user MS is thepersistent resource allocation.

In accordance with yet another aspect of exemplary embodiments of thepresent invention, there is provided an apparatus for transmitting datafrom a Mobile Station (MS) to a Base Station (BS) in a wirelesscommunication system, in which a control channel demodulator demodulatesa downlink signal and receives control information relating to a sharedchannel; a data channel modulator modulates a signal to be transmittedto a radio channel and outputs the modulated signal; and a datamodulation controller determines whether resources of a dedicatedchannel is allocated for a different user MS according to a result ofreceiving the control information and controlling the data channelmodulator to perform a data transmission using remaining resourcesobtained by excluding resources of persistent resource allocation fromthe resources of the dedicated channel when resource allocation for thedifferent user MS is the persistent resource allocation.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a flowchart illustrating a process for transmitting data usingconventional Circuit Switching (CS);

FIG. 2 is a flowchart illustrating a process for transmitting data usingconventional Packet Switching (PS);

FIG. 3 illustrates a process for transmitting voice traffic in aconventional Voice over Internet Protocol (VoIP) service;

FIG. 4 is a flowchart illustrating a method for allocating communicationresources using Virtual Circuit Switching (VCS) in accordance with anexemplary embodiment of the present invention;

FIG. 5 illustrates an example of allocating dedicated channel resourcesfrom a base station to two users in FIG. 4;

FIG. 6 illustrates a process for allocating dedicated channel resourcesfor shared channel resources in accordance with an exemplary embodimentof the present invention;

FIG. 7 is a flowchart illustrating a method for allocating communicationresources using the VCS in accordance with an exemplary embodiment ofthe present invention;

FIG. 8 is a flowchart illustrating a reception method in a mobilestation using the VCS in accordance with an exemplary embodiment of thepresent invention;

FIG. 9 is a block diagram illustrating a structure of a transmitter of abase station in accordance with an exemplary embodiment of the presentinvention;

FIG. 10 is a block diagram illustrating a structure of a receiver of amobile station in accordance with an exemplary embodiment of the presentinvention; and

FIG. 11 is a flowchart illustrating a transmission method of a mobilestation using the VCS in accordance with an exemplary embodiment of thepresent invention.

Throughout the drawings, the same drawing reference numerals will beunderstood to refer to the same elements, features, and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The matters defined in the description such as a detailed constructionand elements are provided to assist in a comprehensive understanding ofexemplary embodiments of the invention. Accordingly, those of ordinaryskill in the art will recognize that various changes and modificationsof the embodiments described herein can be made without departing fromthe scope and spirit of the invention. Also, descriptions of well-knownfunctions and constructions are omitted for clarity and conciseness.

First, a basic concept and terminology defined in exemplary embodimentsof the present invention will be briefly described.

A basic method for allocating communication resources in the presentinvention will be described. When a Circuit Switching (CS) scheme forallocating a dedicated channel and a Packet Switching (PS) scheme forallocating a shared channel are used, the dedicated channel is allocatedto a particular user as in the conventional CS scheme and then the dataof the particular user is transmitted on the allocated dedicated channelwhen data to be transmitted to the particular user is present in atransmission interval. When data to be transmitted to the particularuser is not present, communication resources allocated to the associateddedicated channel are switched to resources of a shared channel of thePS scheme, such that they are used to transmit data of a different user.When the communication resource allocation scheme is used, communicationresources of the dedicated channel are allocated for shared channelresources in a transmission interval in which a data transmission isabsent, such that the efficiency of using communication resources can beimproved.

The communication resource allocation scheme is defined as VirtualCircuit Switching (VCS). Exemplary embodiments of the present inventionwill be described in which an amount of transmission control informationis reduced and a dedicated channel and/or a shared channel aretransmitted and received in the VCS scheme when a transmission time ofan initial transmission packet is defined and a small amount of trafficis frequently transmitted.

FIG. 4 is a flowchart illustrating a method for allocating communicationresources using the VCS scheme in accordance with an exemplaryembodiment of the present invention. FIG. 4 illustrates an example ofallocating and employing communication resources in the VCS scheme in atransmitter of a Base Station (BS).

In step 401 of FIG. 4, the transmitter of the BS allocates the dedicatedchannel by performing a scheduling process for allocating communicationresources to a particular user linked through a radio network. Forexample, to allocate the dedicated channel, a particular Walsh code foridentifying a channel is allocated to a particular user in a wirelesscommunication system using Code Division Multiple Access (CDMA), andparticular subcarrier resources are allocated to a particular user in awireless communication system using Orthogonal Frequency Division Access(OFDMA). To allocate the dedicated channel, the process for allocatingthe particular Walsh code or subcarrier resources to the particular useris conventionally performed in a call setup or handoff process.

On the other hand, FIG. 5 illustrates an example of allocating dedicatedchannel resources from the BS to two Users A and B in step 401 of FIG.4. In FIG. 5, the horizontal axis represents time and the vertical axisrepresents communication resources. In the CDMA system, thecommunication resources represent Walsh codes. In the OFDMA system, thecommunication resources represent subcarriers. In FIG. 5, an uppershaded portion indicates dedicated communication resources allocated toUser A and a lower shaded portion indicates dedicated communicationresources allocated to User B. A portion between the shaded portionsindicates communication resources for which a dedicated channel is notallocated but a shared channel is allocated.

In step 403 of FIG. 4, the transmitter of the BS determines whetherthere is data to be transmitted to a CS user to which a dedicatedchannel is allocated in this transmission interval. Herein, thetransmission interval may be a Transmission Time Interval (TTI) or frameserving as a time unit in which data of one packet is transmitted, ormay be a factor for separating different time intervals in which data istransmitted in a communication system. If data to be transmitted to theCS user is determined to be absent in this transmission interval in step403, the transmitter of the BS switches dedicated channel resourcesallocated to the CS user to shared channel resources during theassociated transmission interval. Then, the transmitter of the BStransmits data of a different PS user on the shared channel in step 405.In this case, control information for data demodulation of the sharedchannel can be sent together with a data transmission through the sharedchannel. However, when a receiver of a Mobile Station (MS) already knowscontent of the control information, the control information may not needto be sent.

If data to be transmitted to the associated CS user is present in thistransmission interval as a determination result of step 403, thetransmitter of the BS determines whether a data packet to be transmittedis an initial transmission packet in step 407. If the data packet to betransmitted is not the initial transmission packet, data is transmittedon the allocated dedicated channel as in the conventional CS scheme. Onthe other hand, if the data packet to be transmitted is determined to bethe initial transmission packet in step 407, the transmitter of the BStransmits data on the allocated dedicated channel at a start point of aframe boundary. After transmitting data on the dedicated channel in step409 or 411, the transmitter of the BS moves to the next transmissioninterval in step 413, determines whether there is data to be transmittedto the associated CS user, and repeats the above process until a call isterminated.

Next, the operation of steps 407 and 411 will be described in detailwith reference to FIG. 5. First, when dedicated channel resources areallocated in the present invention, unique frame boundaries are set on auser-by-user basis as indicated by reference numerals 501 and 502 tomake a limitation such that an initial transmission packet can betransmitted at a start point of a frame boundary in a system forsupporting a Hybrid Automatic Repeat Request (HARQ). The system forsupporting the HARQ divides and transmits one encoder packet many timesin an initial transmission, a first retransmission, a secondretransmission, and the like. In an exemplary implementation, eachtransmission is referred to as a subpacket transmission. The transmitterof the BS transmits each retransmission identifier, that is, a subpacketidentifier serving as control information for notification of a sequencenumber of each subpacket transmission to a receiver of a MS.

As described above, the user-by-user unique frame boundaries are definedto minimize an amount of control information by performing an initialtransmission at the start point of the frame boundary for an associateduser when a subpacket is transmitted to each user. For reference, when aunique frame boundary for a user is defined with respect to a generalpacket and an initial transmission is performed at a start point of theframe boundary, a packet delay time increases and therefore an adverseeffect is caused. However, when a packet with a small amount of datasuch as VoIP traffic is transmitted in a short period, an amount ofcontrol information can be reduced in the present invention.

In FIG. 4, an HARQ based process as indicated by reference numeral 503of FIG. 5 can allocate dedicated channel resources at an equal intervalwhile considering an Acknowledgement/Negative Acknowledgement (ACK/NACK)from a physical layer of a MS. When data to be transmitted to the CSuser is absent in FIG. 4, dedicated channel resources allocated in anassociated transmission interval are switched to shared channelresources and are employed in a data transmission for a different PSuser. It should be noted that the operation of steps 407 and 411 can beoptionally performed to reduce an amount of transmission controlinformation in the communication system supporting the HARQ when aninitial transmission is started in a frame boundary as in steps 407 and411.

FIG. 6 illustrates a process for allocating dedicated channel resourcesfor shared channel resources in accordance with an exemplary embodimentof the present invention.

In FIG. 6, the horizontal axis represents time and the vertical axisrepresents communication resources. In the CDMA system, thecommunication resources represent Walsh codes. In the OFDMA system, thecommunication resources represent subcarriers. In FIG. 6, an uppershaded portion indicates dedicated communication resources allocated toUser A and a lower shaded portion indicates dedicated communicationresources allocated to User B. A portion between the shaded portionsindicates communication resources for which a dedicated channel is notallocated but a shared channel is allocated.

Reference numeral 601 of FIG. 6 denotes a unique frame boundary for UserA, which is indicated similarly by reference numeral 501 of FIG. 5.Reference numeral 602 of FIG. 6 denotes a state in which dedicatedchannel resources for User A are allocated for shared channel resourcescapable of being employed by a different user when data to betransmitted to User A is absent in an associated transmission interval,and corresponds to the operation of step 405 of FIG. 4.

Reference numeral 603 of FIG. 6 denotes a unique frame boundary for UserB, which is indicated similarly by reference numeral 502 of FIG. 5.Reference numeral 605 of FIG. 6 denotes a state in which dedicatedchannel resources for User B are allocated as shared channel resourcesfor a different user when data to be transmitted to User B is absent inan associated transmission interval as indicated by reference numeral604. This state corresponds to the case where a retransmission is nolonger required because an initial transmission has been started at aframe boundary start point for User B and an ACK response has beenreceived from a MS in a second transmission of a packet to betransmitted to User B.

FIG. 7 is a flowchart illustrating a method for allocating communicationresources using the VCS in accordance with an exemplary embodiment ofthe present invention. FIG. 7 illustrates an example of additionallyemploying shared channel resources according to an amount of data to betransmitted for a user.

In step 701 of FIG. 7, the transmitter of the BS allocates a dedicatedchannel by performing a scheduling process for allocating communicationresources to a particular user linked through a radio network. Becausethe dedicated channel allocation is the same as described in FIG. 4, itsdetailed description is omitted for clarity and conciseness.

In step 703, the transmitter of the BS determines whether an amount ofdata to be transmitted to a user to which a dedicated channel has beenallocated in a previous transmission interval is less than or equal tothe capacity of the dedicated channel. If the amount of data to betransmitted to the user is less than or equal to the capacity of thededicated channel, the data is transmitted using the dedicated channelas in the conventional CS scheme in step 705. On the other hand, if theamount of data to be transmitted to the user to which the dedicatedchannel has been allocated is more than the capacity of the dedicatedchannel in step 703, the transmitter of the BS additionally allocatesshared channel resources to the associated user in step 707. In step709, the transmitter of the BS transmits the data of the user on thepre-allocated dedicated channel and the shared channel allocated in step707. Although not illustrated in FIG. 7, control information istransmitted on a shared control channel as in the conventional PS schemebecause the shared channel is used in the data transmission for theassociated user in step 709.

It should be noted that all users cannot use both the dedicated channeland the shared channel as in the exemplary embodiment of FIG. 7. Thatis, the user MS capable of using both the dedicated channel and theshared channel should determine whether its data is transmitted on theshared channel by continuously monitoring the shared control channelduring a call connection. This user MS is selected in advance in theprocess for allocating the dedicated channel in step 701 of FIG. 7.After transmitting the data on the dedicated channel and/or the sharedchannel in step 705 or 709, the transmitter of the BS moves to the nexttransmission interval in step 711 and determines whether data to betransmitted to the associated user is present. Until a call isterminated, the above process is repeated.

Next, a reception method in the user MS using the VCS scheme of thepresent invention will be described with reference to FIG. 8.

FIG. 8 is a flowchart illustrating the reception method in the MS usingthe VCS scheme in accordance with an exemplary embodiment of the presentinvention.

In step 801 of FIG. 8, the user MS is assigned a dedicated channel by aBS. At this time, the BS sends, to the user MS, a message indicatingwhether the shared channel is supported in the channel allocationprocess. When the presence of the shared channel supported between theBS and the MS is predefined and the presence of the shared channelsupported for the MS is preset, the BS can omit an operation for sendingthe message indicating whether the shared channel is supported for theMS in step 801. The user MS receives data using the allocated dedicatedchannel as in the conventional CS scheme and also determines whether itsdata is transmitted on the shared channel by continuously monitoring theshared control channel in step 805. For convenience of explanation, FIG.8 illustrates the process for monitoring the shared control channel instep 805 after receiving the dedicated channel in step 803. However, itshould be noted that the reception of the dedicated channel and thereception of the shared channel are independently performed.

Thus, the user MS continuously monitors the shared control channel todemodulate control information in step 805 and determines that its datais transmitted on the shared channel when a user Identifier (ID) isincluded in the control information in step 807. On the other hand, ifthe user ID is not included in the control information, the user MSdetermines that its data is not transmitted on the shared channel. Whendetermining that the data of the user MS is transmitted on the sharedchannel in step 807, the user MS receives its data by demodulating theshared channel in an associated transmission interval in step 809. Ifthe data of the user MS is absent and the reception of the sharedchannel is completed, the user MS moves to the next transmissioninterval in step 811 and then repeats the process from step 803 until acall is terminated.

Structures of the BS and MS to which the above-described communicationresource allocation method and the reception method are applied will bedescribed with reference to FIGS. 9 and 10.

FIG. 9 is a block diagram illustrating a structure of a transmitter of abase station in accordance with an exemplary embodiment of the presentinvention. FIG. 9 illustrates an example of a structure of a transmitterof the BS applied to a communication system using an OrthogonalFrequency Division Multiplexing (OFDM) transmission scheme.

In FIG. 9, a data buffer 901 temporarily stores data to be transmittedto each user in a downlink after receiving the data from a higher layerof a communication network. According to the capacity of storing data inthe data buffer 901, a resource allocator 903 schedules data to betransmitted to each user and communication resources of each user for adata transmission. In an exemplary implementation, the schedulingoperation of the resource allocator 903 is performed using the method ofFIGS. 4 to 7. An OFDM symbol generator 905 receives transmission targetdata from the data buffer 901 and then generates OFDM symbols to betransmitted under control of the resource allocator 903. The OFDM symbolgenerator 905 can be configured with an encoder, interleaver, symbolmapper, and the like used in the OFDM system.

An OFDM symbol transmitter 907 inserts a Guard Interval (GI) into anOFDM symbol generated from the OFDM symbol generator 905 and thentransmits the OFDM symbol to a radio network. Further, the OFDM symboltransmitter 907 transmits user-by-user data on associated radio channelsin a designated transmission interval according to a scheduling resultof the resource allocator 903. The OFDM symbol transmitter 907 isconfigured with a GI inserter, Radio Frequency (RF) processor, antenna,and the like.

The device of the BS of FIG. 9 is an example of the OFDM system. Thoseskilled in the art will appreciate that the resource allocator 903 usingthe method of FIGS. 4 to 7 is applicable to a device of a BS of athird-generation (3G) network or a transmitter of another communicationnetwork in which packet communication is possible.

FIG. 10 is a block diagram illustrating a structure of a receiver of aMS in accordance with an exemplary embodiment of the present invention.

In FIG. 10, a control channel demodulator 1001 outputs controlinformation from a downlink signal by demodulating a control channel ina predetermined process. Herein, the control information is for a sharedchannel including a user ID, resource information, data rateinformation, modulation information, coding information, and the likewhen the shared channel is used. The output of the control channeldemodulator 1001 is input to a data demodulation controller 1003. Thedata demodulation controller 1003 controls the data channel demodulator1005 to receive the dedicated channel and/or the shared channel as inthe reception method of FIG. 8.

When the data demodulation controller 1003 determines that its data istransmitted on the shared channel according to a result of receiving thecontrol information, it controls the data channel demodulator 1005 todemodulate a signal received from the shared channel in an associatedtransmission interval. Under control of the data demodulation controller1003, the data channel demodulator 1005 demodulates and outputs a datachannel allocated as the dedicated channel and/or the shared channel. InFIG. 10, the control channel demodulator 1001 and the data channeldemodulator 1005 include a structure with a decoder, respectively.

FIG. 11 is a flowchart illustrating a transmission method of a MS usingthe VCS scheme in accordance with an exemplary embodiment of the presentinvention. With reference to FIG. 11, an operation of the MS will bedescribed when the method of the present invention is used for an uplinkdata transmission. It should be noted that the same method is availablefor the downlink data transmission.

In FIG. 11, the MS receives allocation of persistent resources, that is,a dedicated channel, from the BS in step 1101. The MS to which thepersistent resources have been allocated receives and demodulates ashared control channel (or data control channel) in step 1103. The MSretrieves shared control information from the demodulated shared controlchannel and determines whether its allocated persistent resources areallocated to a different user according to the VCS scheme of the presentinvention in step 1105. If the persistent resources allocated to the MSare not allocated to the different user in step 1105, the MS determinesthat its allocated persistent resources are not changed and transmitsdata using the persistent resources in step 1107.

When the MS determines that its allocated persistent resources areallocated to the different user in step 1105, the MS retrieves sharedcontrol information from the shared control channel and determineswhether resource allocation for the different user is persistentresource allocation in step 1109. When determining that the resourceallocation for the different user is not the persistent resourceallocation in step 1109, the MS proceeds to step 1111 to determine thatthe allocated persistent resources are not changed but are the remainingresources obtained by excluding resources temporarily allocated for thedifferent user from the allocated persistent resources available totransmit data of the MS in an associated time. Thus, the MS transmitsthe data using the remaining resources.

When the MS transmits data using the remaining resources obtained byexcluding the resources temporarily allocated for the different userfrom the allocated persistent resources available to transmit data ofthe MS in step 1111, a time interval in which the resources areallocated to the different user may be applied at an associated timepoint or may be a time interval defined for the shared control channelor a time interval preset between the BS and the MS. Further, the timeinterval may have a range from the unique frame boundary for the MS asindicated by reference numeral 603 of FIG. 6 to a start point of thenext boundary.

On the other hand, if the resource allocation for the different user isdetermined to be the persistent resource allocation in step 1109, the MSdetermines that its allocated persistent resources are changed. That is,the MS determines that its new persistent resources are the remainingresources obtained by excluding the persistent resources allocated forthe different user from the persistent resources currently allocated tothe MS in step 1113. The MS transmits the data using the new persistentresources. At this time, it should be noted that the new persistentresources are continuously applied after a resource change is made.Then, the MS repeats the process from step 1103 in the next timeinterval (or slot).

A structure of the transmitter of the MS to which the transmissionmethod of FIG. 11 is applied can be simply implemented using thestructure of the receiver of the MS as described with reference to FIG.10. For example, the control channel demodulator 1001 is maintained inthe transmitter of the MS. In accordance with the present invention, thetransmitter of the MS can be configured with a data modulationcontroller and a data channel modulator mapped to the data demodulationcontroller 1003 and the data channel demodulator 1005.

As is apparent from the above description, exemplary embodiments of thepresent invention can provide a method for allocating communicationresources using the VCS scheme that can efficiently allocate and employthe communication resources by performing communication resourceallocation using both the CS and PS schemes.

Further, exemplary embodiments of the present invention can increasesystem capacity by minimizing a waste of communication resources in awireless communication system for frequently transmitting a small amountof traffic that is sensitive to a delay time.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

1. A method for transmitting data in a Mobile Station (MS) of a wirelesscommunication system, comprising: receiving, by the MS, allocation ofresources for a dedicated channel to the MS from a Base Station (BS);monitoring a shared control channel and receiving control informationfor the data transmission; determining whether resources for thededicated channel are allocated to a different MS while also allocatedto the MS through the control information; transmitting data usingremaining resources excluding the resources allocated to the differentMS when the resources for the dedicated channel are allocated to thedifferent MS; and transmitting data using resources including theresources allocated to the different MS after expiring the allocation ofthe resources for the dedicated channel to the different MS when theresources for the dedicated channel are allocated to the different MSwhile also allocated to the MS, wherein the control informationcomprises information indicating whether the resources for the dedicatedchannel are allocated to the different MS while also allocated to theMS.
 2. An apparatus for transmitting data from a Mobile Station (MS) toa Base Station (BS) in a wireless communication system, comprising: acontrol channel demodulator for demodulating a downlink signal andreceiving control information relating to a shared channel; a datachannel modulator for modulating a signal to be transmitted to a radiochannel and outputting the modulated signal; and a data modulationcontroller for determining whether resources for a dedicated channel areallocated to a different MS while also allocated to the MS through thecontrol information and controlling the data channel modulator totransmit data using remaining resources excluding the resourcesallocated to the different MS when the resources for the dedicatedchannel are allocated to the different MS persistently, wherein thecontrol information comprises information indicating whether theresources for the dedicated channel are allocated to the different MSwhile also allocated to the MS, and wherein the data modulationcontroller controls the data channel modulator to transmit data usingresources including the resources allocated to the different MS afterexpiring the allocation of the resources for the dedicated channel tothe different MS when the resources for the dedicated channel areallocated to the different MS while also allocated to the MS.